1) Butter a square cake pan (large enough to fit the challah in a single layer). Using a small, sharp knife, cut a slit in the bottom crust of each slice of bread to form a pocket in the center. Make the pocket as wide as possible without piercing through the other three sides of each slice. Sprinkle bananas with cinnamon and insert about 6 slices into each piece of bread. Place stuffed bread in a single layer in the buttered pan.

2) Whisk eggs in a medium-sized bowl to blend. Add milk, whipping cream, and vanilla, and whisk until frothy. Pour mixture over bread slices in pan, spooning over the top to coat well. Cover pan tightly with plastic wrap and refrigerate overnight.

3) In the morning, preheat oven to 375°F. Remove the plastic wrap and bake French toast until puffed and just beginning to brown on top, about 25 minutes.

4) Transfer French toast to plates and sprinkle with powdered sugar. Serve with toasted almonds and warm ginger-maple syrup on the side (see recipes below)--or you can use plain maple syrup!